It was just after 7 a.m. April 10 when Courtland Gundling's air conditioner was stolen.

It wasn't the first time one of Gundling's HVAC units left the premises. He has five buildings in the Roselawn area, rental units he operates as part of Dearborn Properties. A few weeks before, Gundling and a neighbor had air conditioners stolen. He replaced his and was hit again.

The second one, he said, really made him mad. So he replaced the unit and waited.

It didn't take long, just two weeks. But this time, Gundling knew as soon as it left the property on Glen Orchard Drive.

The AC unit told him it was leaving.

At 7:17 a.m., he got a text: "I'm on the move."

Someone was stealing the air conditioner at the rental properties. A small GPS he secreted inside the workings of the unit began transmitting when it crossed a geofence set up by the property owner.

A geofence is a virtual geographic boundary defined by GPS technology that enables software to trigger a response when a mobile device enters or leaves a particular area.

The Okeana landlord called a friend and followed the trail. The GPS updated every 60 seconds, so they remained about a minute behind. He called police who eventually caught up with the unit and a suspect at the McDonald's on Reading Road.

Cincinnati Police arrested David Lester Walls, 50, of Linden Street, and charged him with theft and criminal damaging. He was arraigned April 11, pleaded not guilty, and is set to return to court May 15.

Gundling, a retired pilot, said he was surprised at the thefts initially.

"Air-conditioning thefts are down because the price of scrap metal is down," he said. "I didn't expect that."

He said police were surprised the GPS in the AC worked. Gundling was glad it did. "I lost $4,000 in air conditioners," he said. "But in eight years, that's the first major theft we've had."

Gundling said his technology has helped police in the past, with security cameras capturing a shooting and a break-in.

"I have to admit, it felt good. The technology is out there," Gundling said. "I think the guy was shocked. I'm just glad it worked."

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